The invention relates to a rotary pump for producing a pressure medium flow for a consumer. Rotary pumps for producing a pressure medium flow for a consumer that are adjustable in terms of their displacement volume or stroke are known (DE 199 42 466 A1). These rotary pumps have a curved or cam ring that is inserted into a pump housing and which is displaceably or pivotably borne therein. A rotor inserted in the curved ring is driven by a drive shaft and carries at a tangential distance to one another, displacement elements that move along, sliding or rolling on the interior surface of the curved ring. The rotor with the displacement elements can be arranged eccentric to the curved ring so that formed between the displacement elements and the interior surface of the curved ring are pump chambers that have a volume that increases and decreases. A suction opening for supplying fluid to a pump chamber is arranged opposing a pressure opening for removing from another pump chamber a fluid volume that is under pressure.
The curved ring is arranged in a recess of the pump housing and is positioned sealingly, but slidable or pivotable, therein against approximately opposing wall segments. Embodied between the exterior of the curved ring and the wall of the recess in the pump housing is a first pressure chamber and embodied approximately opposite thereto is a second pressure chamber, and these pressure chambers are fluidically separated from one another. The pressure chambers are components of a pressure medium-actuated adjusting device for the curved ring.
A flow control valve controls the pressure in the pressure chambers by adding or removing pressure medium. A low pressure chamber for the flow control valve is connected to a first control line leading from the pressure opening and that is on the downstream side of a metering orifice. A valve plunger actuated with a spring in the low pressure chamber controls the pressure medium actuation of the first and second pressure chambers in a manner known in and of itself.
Rotary pumps are known that have a metering orifice and that are additionally controlled directly or indirectly by the curved ring and which change their orifice cross-section as a function of the position of the curved ring in the pump housing.
The known control systems for a rotary pump are complicated and not optimized in terms of controlling behavior so that these rotary pumps can have increased power losses.